$53 almost smart smoke detector

Ok, the secret to having a reliable, certified, inexpensive smoke detector may be in overlooked option that exists in some industrial smoke detectors - A/C relays. What do you really need in a "smart" smoke detector? For me, knowing which smoke detector went off is what I care about the most. Second is the ability for that information to be used in automation and notification. So, what I really need is a signal wire that tells my system that this particular unit detected something.